In the word often, the labiodental non-sibilant fricative f precedes the alveolar stop t, which is then followed by the vowel e. The Oxford Dictionaries Online offers two accepted pronunciations:
I would like to describe the phonetic interaction between the f and the t in the pronunciation
/ˈɒf(ə)n/. The sole pronunciation of the archaic oft, leads me to consider that the vowel plays a significant role in silencing the t. Though I doubt it is the standard terminology, I would tend to describe it in laymen's terms with the word picture underlying fricative:
the fricative rubs out the stop in concert with the vowel
If that seems like an acceptable description, I would be content with it, but I would like to know if there is a more precise professional description of that phonetic effect.